INT 15 - TopViewTopView, DESQview, TaskView, OmniView, other compatibles - "GETBUF" - GET VIRTUAL SCREEN INFO
	AX = 1024h
	BX = segment of object handle for window (0000h = use default)
Return: ES:DI -> virtual screen
	CX = size of virtual screen in bytes
	DL = screen type
	    00h text screen
	    01h graphics screen
SeeAlso: INT 10/AH=FEh,INT 21/AH=2Bh/CX=4445h